The invention is concerned with electro-optical modulator arrays and particularly modulators for use in integrated optical devices. Light in an optical channel or waveguide is modulated by means of an electric field which functions to change the index of refraction of the media used in forming the waveguide, and therefore change the waveguide mode type, propagation direction, or intensity distribution among a number of channels of the light propagating therein. Generation of such electric fields are generally done external to the electro-optical crystal and additional hardware is required for providing the electric field generating means as well as the control means for governing the amplitude and sequence of the electric field.
One closely related prior art electro-optical modulator array is described in U.S. Pat. No. 3,841,733, which discloses an optical waveguide system for producing a line of modulated radiation data, including a plurality of electro-optical modulators. U.S. Pat. No. 4,003,632 describes a similar structure which incorporates a floating gate as a charge storage structure. Such a floating gate may be associated with a semiconductor memory element, and information written into or read from such memory element by the light propagating in the waveguide exciting or discharging the stored electronic charges. U.S. Pat. No. 4,094,606 describes a plurality of optical waveguides positioned between a common electrode and individual electrodes arrayed along a charge coupled device.
In all of these prior arrays, not much attention is directed to the external electronics necessary to produce and control the electric field and the mechanism of applying the electric field to the integrated optical modulator array in a compact fashion. Such array designs are disadvantageous in many applications where a light, compact modulator array structure is necessary. Prior to the present invention there has not been a simple and easily fabricated integrated structure for modulating light in a large number of electro-optical channels on an integrated optical structure.